<?php

namespace App\Third\Service\Wx;


class WxCryptService
{

    public static function encrypt($input, $key)
    {
        //key为密钥 S2
        $key = WxCryptService::reflowNormalBase64($key);
        @$size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_ECB);
        $input = WxCryptService::pkcs5_pad($input, $size);
        @$td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_ECB, '');
        @$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
        @mcrypt_generic_init($td, base64_decode($key), $iv);
        @$data = mcrypt_generic($td, $input);
        @mcrypt_generic_deinit($td);
        @mcrypt_module_close($td);
        $data = base64_encode($data);
        $data = WxCryptService::reflowURLSafeBase64($data);
        return $data;
    }


    public static function decrypt($sStr, $sKey)
    {
        //sKey为密钥 S2
        $sStr = WxCryptService::reflowNormalBase64($sStr);
        $sKey = WxCryptService::reflowNormalBase64($sKey);
        @$decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128,
            base64_decode($sKey), base64_decode($sStr),
            MCRYPT_MODE_ECB);
        $dec_s = strlen($decrypted);
        $padding = ord($decrypted[$dec_s - 1]);
        $decrypted = substr($decrypted, 0, -$padding);
        return $decrypted;
    }


    private static function reflowURLSafeBase64($str)
    {
        $str = str_replace("/", "_", $str);
        $str = str_replace("+", "-", $str);
        return $str;
    }


    private static function reflowNormalBase64($str)
    {
        $str = str_replace("_", "/", $str);
        $str = str_replace("-", "+", $str);
        return $str;
    }


    private static function pkcs5_pad($text, $blocksize)
    {
        $pad = $blocksize - (strlen($text) % $blocksize);
        return $text . str_repeat(chr($pad), $pad);
    }

}